NEVERS, France (VN) — When Giant Bicycles first launched their Propel aero bike four years ago the only weak spot in an otherwise fantastic, fast package was the brakes, a pair of mushy mini-Vs that served to decrease both drag and the ability to stop. That issue is now behind us. Giant’s all-new, completely redesigned range of Propel bikes is equipped with Shimano disc brakes, and Giant says they’re faster than ever — and faster than the competition.
The Giant Propel Advanced Disc range has been in development for three years and the new disc bike was first spotted in July at the Tour de France under Michael Matthews (Team Sunweb). Matthews sprinted to third on stage 7 at the Tour atop the new Propel Disc.
Giant started with the discs and built the bike around them. That means the Propel has an entirely new geometry and tube shaping compared to the old model. The company brought nothing from the previous generation rim-brake Propel, it says. Leaving those v-brakes behind is just fine, but did they hit the mark elsewhere?
Since this is an aero bike, aero came first. Giant designed the bike at Aero Concept Engineering’s (ACE) wind tunnel at the Magny-Cours formula 1 racetrack in Nevers, France. The tunnel was originally designed for low-speed testing and operates on a closed loop circuit — both important to acquiring reliable data on a bicycle.
Giant’s relationship with ACE dates back to the first edition rim-brake Propel. With a mannequin mounted to the bike, Giant has what it believes is the best model for optimizing the design of the frame for real world conditions. Giant tested against the Trek Madone, Specialized Venge, and other top frames, and claims the Propel is fastest using its testing methods. Giant also claimed that its new Propel is faster than the old Propel. As of press time, Giant had not yet provided the actual data to back up these claims, though it says it’s coming.
The original Propel tested well in VeloNews’s own wind tunnel testing, besting top competitors like the Trek Madone (the old 2013 model). Giant tested its new Propel on its own and with the mannequin, both in a stationary position and pedaling to simulate a real rider. The aerodynamics were determined through testing at a yaw angle of zero to 30 degrees.
Giant claims the range’s top-of-the-line model, Propel Advanced SL Disc 0, frameset is 45g lighter than its rim-brake counter-part. The frameset weighs 2,145 grams. When developing the disc bike, Giant analyzed their competitors aero bikes as well, specifically the Specialized Venge Vias Disc, Trek Madone (rim-brake version as Madone disc doesn’t exist yet), and Canyon Aeroad CF SLX disc. According to Giant, their Propel disc frameset is 414 grams lighter than the Venge and 229 grams lighter than the Madone. The Canyon comes out 60 grams lighter than the Propel disc.
Giant claims that its new Propel is stiffer than these competitors as well. Each frame was locked at the rear dropouts with lateral force applied to the fork to determine the frame’s stiffness.
A quick word on integration. The cockpit of aero road bikes always seem to be an issue. Giant, as with so many others, went with an integrated, two-part handlebar/stem combo. The handlebar and stem are two separate pieces, so the rider is able to adjust the length of the stem and width of the handlebar to their liking. The integration of the two is proprietary, so one must use Giant’s aero handlebar and stem. Due to the integration of the handlebar and stem, you are unable to adjust the position of the actual handlebar. The rider is stuck with the angle of the drops that come stock.
Furthermore, the stem is designed such to fully integrate Shimano’s shifter cables, either Di2 or mechanical depending on the model, and their hydraulic cable system. This leaves a sleek and clean looking flight deck.
Aero handlebars and integration at the front of the bike can decrease drag significantly. Just know that any integrated system is going to be less user-friendly.
Wheels and discs
All bikes in the new range come equipped with 140mm rotors on the front and rear. Giant says 140mm rotors provide plenty of stopping power and there is no need for 160mm rotors (despite the fact that Shimano recommends them). The front disc caliper is tucked neatly behind the fork. Giant said they weren’t too worried about caliper integration and drag created by the caliper, as the air is already “dirty” by the time it gets to that point, as the air has already come in contact with the tire, wheel and fork.
With a new Giant aero disc bike also comes all new aero disc wheels, the SLR 0 and SLR 1. Both versions come in three depths, 65mm, 42mm, and 30mm. All of the Propel Advanced disc range bikes come stocked with the 42mm wheel on the front, which Giant believes is necessary to fight crosswinds, and 65mm on the rear.
The SLR 0 65 Disc wheelset is going to set you back $2,300, or you can opt for the 42mm and 30mm SLR 0 versions for $100 less. The SLR 1 is considerably more affordable at $1,500 for the 65mm and $1,400 for the 42mm and 30mm. What you get for that higher cost for the zero is 100 fewer grams of weight, not an insignificant difference.
The bike uses thru axles, which means racers must still deal with cumbersome wheel changes. The wheels come equipped with a new tubeless tire, the Gavia AC, available in two versions, zero and one. The Gavia AC 0 has a tpi of 170, making it thinner, and lighter, with claimed lower rolling resistance. The Gavia AC 1 has a tpi of 60. Both versions are available in 25c or 28c sizes with an all-condition tread.
One new feature — Giant has developed a new tubeless system that allows them to ship the bikes with the tubeless wheels already set-up and ready to go out of the box.
The Giant Propel Advanced Disc range consists of four bikes, starting at $3,700 and topping out at $11,300. The higher the price tag, the lighter the components and the greater the aerodynamic integration. Color schemes are limited to those shown on the different bikes.
Giant Propel Advanced SL 0 Disc: $11,300
Giant Propel Advanced SL 1 Disc: $7,000
Giant Propel Advanced Pro Disc: $5,700
Giant Propel Advanced Disc: $3,700
Currently, there is no plan to create a rim-brake version of the new frame, but the folks at Giant say, “never say never.”
I had the opportunity to test the top model, the Propel Advanced SL Disc 0. The bike came equipped with Shimano Di2 and while the test bike did not have a power meter, Giant said Shimano’s power meter will come stock with bike.
One thing to note on the two SL versions of the bike: The seatpost is integrated. While there is the ability to add spacers, it will be important to make sure you know your seat height before cutting.
The first noticeable feature is the width of the handlebars. Riders with small hands will find them to be a bit too big. While it is possible to change the width or length of the overall handlebar, Giant’s integrated handlebar/stem design has made it impossible to change the diameter of the upper part of the handlebar.
When taken for a test-ride on the Magny-Cours racetrack, I was able to put the bike through its paces with the tracks u-turns, fast downhill chicanes, and tight 90-degree corners. The 140mm rotors provided plenty of stopping power. As a light rider, even though I live in the mountains of Colorado, I can’t foresee needing larger rotors.
On the slick surfaces of the track, the Propel disc felt like an aero race bike should, smooth and fast. The front-end stiffness allows you to corner with speed and gives you the confidence to ride the corner out.
When taken off the smoother racetrack and onto the rough rolling hills of the Burgundy region of France, the bike tells a different story. The wide, flat top of the top of the handlebar takes a moment to get used to. I found myself hitting my knees on it earlier in the ride.
Frankly, the hyper-stiff frame makes for a somewhat uncomfortable ride. That’s a sentence that could be used to review every aero bike ever, though.
The bike is made as an aero road bike should be — super fast on the flats. On rolling hills, the stiffness of the frame creates a heavy feeling when out of the saddle, especially for a lighter rider. Descending, though, is no issue. The disc brakes and frame stiffness translate to taking the corners not only faster, but more confidently.
Overall, the new Propel Advanced SL Disc 0 is optimized to reduce draft when riding at top speeds. For the power racer, it offers a blend of aerodynamics and fast handling. The bike is made for a flat stage of the Tour de France and your weekend criterium, but as with aero bikes, not a tool for toodling about.